Purpose: Endometriosis can significantly impair the quality of life of those affected. Multimodal self-help measures are recommended but often difficult to access. Smartphone apps have been shown to improve quality of life for other conditions with chronic pain. The aim of this study was to examine whether there is evidence of beneficial effects of the smartphone app “Endo-App®” and whether a multicenter randomized controlled trial should be planned to substantiate these effects. Methods: In a sample of N=106 women affected by endometriosis the present study determined the influence of the use of Endo-App ® on their quality of life. Among others, the validated questionnaire Endometriosis Health Profile from Oxford University was used for this purpose. Results: The use of Endo-App ® lead to a highly significant improvement in quality of life already after two weeks. A statistically significant change was found for nine out of ten measured variables of quality of life. A series of further analyses validated that the measured positive effects were not due to other confounding factors. Conclusion: In summary, the results indicate that the quality of life of women with endometriosis improved by the digital self-management tool Endo-App ®. More studies are needed to further explore the influence of the app on quality of life and as confirmatory evidence of beneficial effects. For this purpose, a randomized controlled trial should be conducted over a longer period of time. Trial registration: This trial is registered at clinicaltrials.gov under the registration number NCT05528601 on August 18, 2022. It was retrospectively registered.